jrouter/aurp/routing_info.go
2024-03-31 09:31:50 +11:00

229 lines
4.7 KiB
Go

/*
Copyright 2024 Josh Deprez
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package aurp
import (
"encoding/binary"
"fmt"
"io"
)
type RIReqPacket struct {
Header
}
type RIRspPacket struct {
Header
Networks NetworkTuples
}
func (p *RIRspPacket) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
a.writeTo(&p.Header)
a.writeTo(p.Networks)
return a.ret()
}
func parseRIRsp(p []byte) (*RIRspPacket, error) {
n, err := parseNetworkTuples(p)
if err != nil {
return nil, err
}
return &RIRspPacket{
Networks: n,
}, nil
}
type RIAckPacket struct {
Header
}
type RIUpdPacket struct {
Header
Events EventTuples
}
func (p *RIUpdPacket) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
a.writeTo(&p.Header)
a.writeTo(p.Events)
return a.ret()
}
func parseRIUpd(p []byte) (*RIUpdPacket, error) {
e, err := parseEventTuples(p)
if err != nil {
return nil, err
}
return &RIUpdPacket{
Events: e,
}, nil
}
type NetworkTuples []NetworkTuple
func (n NetworkTuples) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
for _, nt := range n {
a.writeTo(&nt)
}
return a.ret()
}
func parseNetworkTuples(p []byte) (NetworkTuples, error) {
// Each network tuple is at least 3 bytes, so we need to store at most
// len(p)/3 of them.
n := make(NetworkTuples, 0, len(p)/3)
for len(p) > 0 {
nt, nextp, err := parseNetworkTuple(p)
if err != nil {
return nil, fmt.Errorf("parsing network tuple %d: %w", len(n), err)
}
n = append(n, nt)
p = nextp
}
return n, nil
}
type NetworkTuple struct {
RangeStart uint16
Distance uint8
RangeEnd uint16
// 0x00 for extended tuples
}
func (nt *NetworkTuple) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
a.write16(nt.RangeStart)
if nt.RangeStart == nt.RangeEnd {
// non-extended tuple
a.write8(nt.Distance)
return a.ret()
}
// extended tuple
a.write8(nt.Distance | 0x80)
a.write16(nt.RangeEnd)
a.write8(0x00)
return a.ret()
}
func parseNetworkTuple(p []byte) (NetworkTuple, []byte, error) {
if len(p) < 3 {
return NetworkTuple{}, p, fmt.Errorf("insufficient input length %d for network tuple", len(p))
}
var nt NetworkTuple
nt.RangeStart = binary.BigEndian.Uint16(p[:2])
nt.RangeEnd = nt.RangeStart
nt.Distance = p[2]
if nt.Distance&0x80 == 0 {
return nt, p[3:], nil
}
if len(p) < 6 {
return NetworkTuple{}, p, fmt.Errorf("insufficient input length %d for extended network tuple", len(p))
}
nt.Distance &^= 0x80
nt.RangeEnd = binary.BigEndian.Uint16(p[3:5])
return nt, p[6:], nil
}
type EventTuples []EventTuple
func (e EventTuples) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
for _, et := range e {
a.writeTo(&et)
}
return a.ret()
}
func parseEventTuples(p []byte) (EventTuples, error) {
// Each event tuple is at least 4 bytes, so we need to store at most
// len(p)/4 of them.
e := make(EventTuples, 0, len(p)/4)
for len(p) > 0 {
et, nextp, err := parseEventTuple(p)
if err != nil {
return nil, fmt.Errorf("parsing event tuple %d: %w", len(e), err)
}
e = append(e, et)
p = nextp
}
return e, nil
}
type EventTuple struct {
EventCode EventCode
RangeStart uint16
Distance uint8
RangeEnd uint16
}
func (et *EventTuple) WriteTo(w io.Writer) (int64, error) {
a := acc(w)
a.write8(uint8(et.EventCode))
a.write16(et.RangeStart)
if et.RangeStart == et.RangeEnd {
// non-extended tuple
a.write8(et.Distance)
return a.ret()
}
// extended tuple
a.write8(et.Distance | 0x80)
a.write16(et.RangeEnd)
return a.ret()
}
func parseEventTuple(p []byte) (EventTuple, []byte, error) {
if len(p) < 4 {
return EventTuple{}, p, fmt.Errorf("insufficient input length %d for network event tuple", len(p))
}
var et EventTuple
et.EventCode = EventCode(p[0])
et.RangeStart = binary.BigEndian.Uint16(p[1:3])
et.RangeEnd = et.RangeStart
et.Distance = p[3]
if et.Distance&0x80 == 0 {
return et, p[4:], nil
}
if len(p) < 6 {
return EventTuple{}, p, fmt.Errorf("insufficient input length %d for extended network event tuple", len(p))
}
et.Distance &^= 0x80
et.RangeEnd = binary.BigEndian.Uint16(p[4:6])
return et, p[6:], nil
}
type EventCode uint8
const (
EventCodeNull EventCode = 0
EventCodeNA EventCode = 1
EventCodeND EventCode = 2
EventCodeNRC EventCode = 3
EventCodeNDC EventCode = 4
EventCodeZC EventCode = 5
)